This invention relates to a device and method for adjusting damping in a vehicle shock absorber.
Vehicles utilize shock absorbers to dampen vibrations and shocks experienced by a vehicle. Variations in payload and ground conditions can affect vehicle control and handling. Having the ability to selectively adjust the damping force in a shock absorber is desirable to improve vehicle control and handling in response to these variables. Some shock absorbers include position sensing technology and damping adjustment that permit a vehicle operator to selectively change damping to a desired level.
Current adjustment systems rely on external components or adjuster modules to provide adjustment. Utilizing additional components significantly increases cost and assembly time. Thus, the adjustment feature is not typically incorporated on most vehicles.
It is desirable to provide a shock absorber with an adjustment mechanism that utilizes components already found within the shock absorber, and which can be easily adjusted by a vehicle operator to control damping levels. The adjustment mechanism should also be cost effective in addition to overcoming the above referenced deficiencies with prior art systems
The subject invention provides a shock absorber that includes damping adjustment for a twin cylinder configuration having an inner cylinder mounted within an outer cylinder in a spaced relationship to form a flow gap. Simultaneous and/or independent compression and rebound damping adjustment is achieved by moving the outer cylinder with respect to the inner cylinder to adjust flow gap size around flow ports formed within the inner cylinder. The outer cylinder can be rotated or axially translated relative to the inner cylinder to adjust gap size.
In the preferred embodiment, this is accomplished by the outer cylinder having an eccentric inner diameter to outer diameter profile to control the width of the flow gap is in relation to the ports. The outer cylinder forms an outer wall of the shock absorber and the inner cylinder forms an inner wall of the shock absorber. The outer wall is defined by an outer diameter that has a first center and an inner diameter that has a second center that is different than the first center to form the eccentric profile. The eccentricity of the outer wall adjusts flow gap size as the outer cylinder is rotated or translated to adjust damping. The eccentricity is formed by varying the wall thickness or profile of the outer cylinder. Multiple eccentricities to provide multiple gap size variations are achieved by forming the outer wall with several different thicknesses about the circumference.
In one embodiment, the eccentricity is uniform such that the gap is uniform in cross-section along the length of the cylinders. The shock absorber is adjustable between a low damping force where the gap size is defined by a first width in relation to the ports and a high damping force where the gap size is defined by a second width in relation to the ports that is less than the first width.
In an alternate embodiment, the eccentricity is variable such that the gap is nonuniform in cross-section along the length of the cylinders. The variable eccentricity results from an inner surface of the outer wall having a stepped or tapered profile. The steps or taper provide variable gap widths for each of the ports.
These and other features of the present invention can be best understood from the following specification and drawings, the following of which is a brief description.